1. Field of the Invention
The invention relates to devices used in endoscopic surgical procedures. In particular, the invention relates to pressure sensing devices used in arthroscopic surgical procedures. Still more particularly, the invention relates to pressure sensing scope sheaths used in arthroscopic surgical procedures in order to simultaneously provide instrument or scope access to the arthroscopic work site while also providing a means for communicating pressure information from the work site, a means for fluid inflow and a means for fluid outflow.
2. Description of the Prior Art
In endoscopic surgical procedures and, in particular, in arthroscopic procedures, there is often a need to know the pressure at the surgical work site. For example, in some arthroscopic surgical procedures the joint being operated on is subjected to irrigating fluid pressure in order to distend the joint to provide an adequate work space and in order to keep the joint free of debris while enhancing visibility during the procedure. An outflow channel is provided to maintain fluid movement through the work site. The fluid may be pressurized by a pump which forces the fluid into the work site, or it may simply be pressurized by gravity. While a certain degree of pressure is necessary, an excessive amount of pressure may cause extravasation into surrounding tissue or otherwise injure the patient. Consequently, pressure sensing devices are used during many arthroscopic surgical procedures in order to control the fluid pressure being supplied to the work site.
Pressure sensing devices may be provided in a variety of configurations depending upon the surgeon's preference and the particular surgical procedure. Also, different surgical techniques require a different number of portals to gain access to the surgical site. Common techniques for operative arthroscopy require two or three portals at the work site while diagnostic arthroscopy may be performed with two portals. For example, in arthroscopic surgery of the knee using a three-portal technique, one pressure sensing cannula assembly may be provided through one portal in the knee while a second portal is used for an arthroscope and a third portal is used for an operating instrument such as a powered rotary shaver system. The pressure sensing cannula has two channels: one for inflow to communicate the pressurized fluid to the knee capsule and another to communicate pressure to a pressure sensor.
Alternatively, a dedicated pressure sensing cannula in one portal may be provided to provide pressure sensing information to a sensor while another cannula in another portal may be used to provide instrument access and a third cannula in a third portal may be used to provide access for an arthroscope (or the scope may be used without a cannula).
Another prior art system utilizes a dual stopcock pressure sensing scope sheath designed to work with a particular pump system made by the same manufacturer. This sheath has a central, axial lumen for scope access and a surrounding annular channel joined to separate inflow and outflow stopcocks at its proximal end. The stopcocks share this single annular channel which is used alternatingly for both inflow and outflow. The annular space between the scope and the inside of the central cannula provides pressure information to a port at the proximal end of the sheath. While this system may be used with only a two portal technique, the alternating nature of the system operation makes many surgeons use it in a three portal technique, with the third portal used for pressure sensing.
There is a preference to minimize the number of portals required in endoscopic and arthroscopic procedures. Consequently, it is an object of this invention to provide a surgical instrument which can provide access to an endoscopic surgical work site while minimizing the number of portals required by utilizing a single portal for pressure sensing information in addition to fluid inflow and fluid outflow.
It is also an object of this invention to provide a single instrument having a plurality of channels capable of performing fluid inflow, fluid outflow and pressure sensing simultaneously.
It is an additional object of this invention to provide a method for sensing pressure using such an instrument.
It is yet another object of this invention to provide a cannula or sheath which can receive a scope therethrough while simultaneously enabling a user to perform fluid inflow, fluid outflow and pressure sensing.